Proceedings of the International Conference “Embedded Electronics and
Computing Systems(EECS)” 29-30 July, 2011 by S K R engineering
COLLEGE,CHENNAI-600123
EDGECRYPT ENCRYPTION ALGORITHM FOR MEDICAL
IMAGE-A LOSSLESS APPROACH
V.D.Ambeth Kumar1, R.Preethika2, A.Muthuselvi3
1,2. Lecturer, Asst.Prof, CSE, Panimalar Engineering College, Chennai.
3. UG Student, CSE, Panimalar Engineering College, Chennai.
ABSTRACT
In this paper, we are
proposed that the topic related to
Encryption, you may beware about
the term Encryption. My paper
deals with a lossless Encryption
method for Encrypting Medical
Images using the Information
contain with in an Edge map.
Image Encryption is an
effective approach for providing
security and privacy protection for
Medical Images. This paper
introduced new lossless approaches,
called Edge Encrypt for Encrypting
Medical Images. This algorithm can
fully protect the selected objects (or)
regions within Medical Images (or)
the Entire Medical Images. This
algorithm can also Encrypt the other
types of Images such as gray Scale
Images (or) colour Images. It can
also be used for privacy protection
such as wireless medical network
and mobile medical services.
Keywords: Lossless Encryption,
EdgeCrypt, Medical Image.
INTRODUCTION
Medical
images
are
generated by using different
technologies of medical imaging for
many clinical applications to
diagnose or examine diseases. These
technologies include radiography,
Computed
Tomography
(CT),
Magnetic
Resonance
Imaging
(MRI), Photoacoustic imaging, and
many others. Medical images may
contain a large amount of private
and important information about
patients. Some of them may be
included in a patient’s medical
record along with text based
personal
information,
clinical
diagnosis and examination records.
They may be archived as digital
formats in the computer or
transmitted among hospitals or
doctors for various clinical services.
Some rapidly growing new clinical
services such as telemedicine and ehealth transmit medical information
over telephone or
networks.
Providing security of medical
images becomes an important issue
for hospitals and medical service
organizations. Image encryption is
an effective method to secure
medical images while preserving
their integrity.
Many
approaches
for
medical image encryption have been
developed in recent years. For
example
Meghdad Ashtiyani
(et al) [1]and two others proposed an
Encryption Scheme for Encryption
of Medical Images based on
combination of Scrambling & a
confusion chaotic cat map is used for
the scrambling the address of
Medical Image pixels. In order to
provide security for the scheme as
modified form of simplified version
of advanced Encryption standards is
introduced and applied.
The
modification is that we make use of
chaos for s-box design & replace it
with that of S-AES & it has all
cryptography characteristics and
requirement of S-AES. Hence the
main contribution of this work is that
we make use of chaos in both Image
diffusion of this work is that we
make use of chaos in both Image
diffusion and confusion parts. In
Proceedings of the International Conference “Embedded Electronics and
Computing Systems(EECS)” 29-30 July, 2011 by S K R engineering
COLLEGE,CHENNAI-600123
order to check the performance of
the
method
Experimental
Implementation has been done.K.C.
Rachshankar and two others [2]
Image Security has found a great
need in many applications where the
info which is in the form of Image is
to be protected from unauthorized
access. This is possible by
Encrypting the Image, then by
improving the security of the image,
there are several schemes for Image
Encryption that have been proposed.
These
schemes
produced
Randomness in the image and hence
the content is not visible. But
Encryption and decryption consume
a considerable amount of time hence
there is a need for an efficient
algorithm. In this paper we improve
the efficiency of the algorithm
through a region based selective
Image Encryption technique, which
provides the facility of selective
Encryption
and
selective
Reconstruction
of
images.
Koredianto Usman and two others
[3] describe the result of complete
investigation and utilization pixels
arrangement
and
Random
permutation to Encrypt the medical
image for transmission security. The
main objective is to obtain a high
speed computation process together
with high security compare to other
algorithm such as transform method
and traditional method. The pixels
arrangement and permutation does
not
need
any
mathematical
manipulation.
Their
feature
especially very useful for medical
image where the image can very big.
Tenting result using gray scale
image shows a good randomness and
quick compilation process. Zalia
Brahim
and
others
[4]
implemented
a
novels
selective Encryption image scheme
based on JPEG 2000 which Encrypts
only the code blocks corresponding
to some sensitive precincts. In order
to improve the security level we
introduced the permutation of code
blocks contributing in the selected
precincts. Symmetric Encryption
AES with CFB mode is used to
Encrypt swapped code blocks. The
reason
behind
combining
permutation
and
selective
Encryption is to minimize the
amount of procured data Encryption
ensuring
the
best
possible
degradation through the permutation.
PROPOSED METHOD
In this section, we introduce
a new algorithm, EdgeCrypt, to
encrypt medical images using an
edge
map.
The
underlying
foundation of the EdgeCrypt
algorithm is to encrypt medical
images via changing image data. It
obtains the edge map of the medical
image by applying a specific type of
edge detector such as Canny, or
Sobel, or Prewitt, or any other, with
a certain threshold value. The
algorithm then decomposes the
medical image into several binary bit
planes, encrypts all bit planes by
performing an XOR operation
between the edge map and each bit
plane, encrypts the edge map using a
random bit sequence generated from
the logic chaotic map, interleaves the
encrypted edge map among the
XORed bit planes, reverses the order
of all bit planes, and combines them
to obtain the final encrypted medical
images.The block diagram of the
EdgeCrypt algorithm is shown in
Fig. 1.
Proceedings of the International Conference “Embedded Electronics and
Computing Systems(EECS)” 29-30 July, 2011 by S K R engineering
COLLEGE,CHENNAI-600123
EDGE
DETECTOR
Threshold
Value
ORIGINAL
MEDICAL
IMAGE
EDGE MAP
+
+
BIT PLAN
XOR
BIT PLAN
+
RANDOM BIT
SEQUENCE
INVERSE OF
ALL BIT PLAN
LOGIC
CHAOTIC MAP
ENCRYPTED
MEDICAL IMAGE
Fig 1. Encryption method
In the decryption process, the
authorized users do not have to
know the type of the edge detector
and its threshold value to reconstruct
the original image because the edge
map has been sent to users along
with the encrypted image. However,
the edge map can be completely
recovered only by using the correct
security keys: the location to
interleave the edge map as well as
the initial condition x0 and
parameter r of the logic chaotic map.
The decryption process first
decomposes the encrypted image
into binary bit planes. It then
reverses the order of all bit planes
and extracts the edge map from the
bit planes. The edge map is
reconstructed using security keys.
The algorithm performs an XOR
operation between the edge map and
each bit plane and combines the
Proceedings of the International Conference “Embedded Electronics and
Computing Systems(EECS)” 29-30 July, 2011 by S K R engineering
COLLEGE,CHENNAI-600123
XORed bit planes to obtain the
reconstructed
medical
image.
Decrypt algorithm is shown in Fig.
2.
Initial
Parameter Y
Condition X
ENCRYPTED
MEDICAL IMAGE
LOGIC CHAOTIC
MAP
INVERSE
OF ALL BIT
PLAN
RANDOM BIT
SEQUENCE
+
+
BIT PLAN
+
XOR
BIT PLAN
EDGE MAP
EDGE
DETECTION
\
ORIGINAL MEDICAL
IMAGE
Fig 2. Decryption method
EXPERIMENT AND RESULTS
DISCUSSION
The EdgeCrypt algorithm has
been successfully implemented in
more than 16 medical images. Some
simulation examples are presented in
this section to show the performance
of the algorithm for medical image
encryption. A comparison is made
with the AES algorithm to show the
Proceedings of the International Conference “Embedded Electronics and
Computing Systems(EECS)” 29-30 July, 2011 by S K R engineering
COLLEGE,CHENNAI-600123
encryption
efficiency
of
the
EdgeCrypt algorithm. The algorithm
is also proved to be able to encrypt
the selective objects /regions and
other types of images. The
interleaved location of the edge map
in all examples in this section is the
between the first bit plane, which
contains the most significant bits of
all image pixels, and the second bit
plane which contains the second
most significant bits of image pixels.
Fig.3 gives an example of the MRI
image encryption. The encrypted
image in Fig.3 (c) is completely
different from the original MRI
brain image in Fig.3 (a). The
histogram in Fig.3 (g) shows the
nearly equal distribution of the pixel
values in encrypted image. This
makes the encrypted image difficult
to be broken by attacks.
The original image can be protected
with high level of security. This is
one of advantages of the presented
algorithm.The original image has
been completely reconstructed. The
reconstruction can be verified from
the reconstructed image in Fig.3(d)
and its histogram in Fig.3(h) because
both of them are exactly the same as
the original image. The edge map in
this example is generated by the
Sobel edge detector with threshold
0.5. It is encrypted by logic chaotic
map with the initial condition 0 x =
0.6 and the parameter r = 3.65 .
Fig. 3. MRI image encryption. (a) The original MRI image; (b) The edge map obtained by Sobel edge
detector with threshold 0.5; (c) The encrypted MRI image, (d) The reconstructed MRI image; (e) Histogram
of the original MRI image; (f) The encrypted edge map,x0=0.6, r=3.65 ; (g) Histogram of the encrypted MRI
image; (h) Histogram of the reconstructed MRI image.
CONCLUSION
In this paper, we have
introduced a new algorithm for
medical image encryption which
uses the edge map. The algorithm
encrypts
medical
images
by
combining four different processes
to change image data. The nearly
equal data distribution of the
encrypted medical image has been
obtained after several encryption
processes.
The users have flexibility to
choose any existing edge detector
and its threshold values for the
EdgeCrypt algorithm or interleave
the edge map between any two bit
planes. The security keys of the
EdgeCrypt algorithm have an
infinite
number
of
possible
combinations. This ensures the
Proceedings of the International Conference “Embedded Electronics and
Computing Systems(EECS)” 29-30 July, 2011 by S K R engineering
COLLEGE,CHENNAI-600123
unauthorized users have difficulty to
decode the encrypted medical
images. Thus, original medical
images are protected with a high
level of security.
Experimental examples have
demonstrated that the EdgeCrypt
algorithm is a lossless encryption
method and can fully encrypt
selected objects or regions within the
medical images or entire medical
images. The EdgeCrypt algorithm
can be used for real-time medical
applications such as wireless
medical networking and mobile
medical services. It can overcome
the plaintext attacks.
REFERENCES
[1]. M.Ashtiyani, P. M. Birgani, and
H. M. Hosseini, "Chaos-Based
Medical Image Encryption Using
Symmetric
Cryptography,"
in
Information and Communication
Technologies: From Theory to
Applications, 2008. ICTTA 2008.
3rd International Conference on,
2008, pp. 1-5.
[2]. Y. Ou, C. Sur, and K. Rhee,
"Region-Based Selective Encryption
for Medical Imaging," in Frontiers
in Algorithmics, 2007, pp. 62-73.
[3]. K. Usman, H. Juzoji, I.
Nakajima, S. Soegidjoko, M.
Ramdhani, T. Hori, and S. Igi,
"Medical Image Encryption Based
on Pixel Arrangement and Random
Permutation
for
Transmission
Security," in e-Health Networking,
Application and Services, 2007 9th
International Conference on, 2007,
pp. 244-247.
[4]. Z. Brahimi, H. Bessalah, A.
Tarabet, and M. K. Kholladi, "A new
selective encryption technique of
JPEG2000 codestream for medical
images transmission," in Systems,
Signals and Devices, 2008. IEEE
SSD 2008. 5th International MultiConference on, 2008, pp. 1-4.